Kacy Clemens, top center, takes a picture with his family during a ceremony for his intent to attend Texas on a baseball scholarship, Wednesday, Nov. 14, 2012, in Memorial High School in Houston. His brother Kody Clemens, top left, grandmother Jan Wilde, top right, brother Koby Clemens, bottom left, and mother Debbie Clemens. ( Nick de la Torre / Houston Chronicle )

Kacy Clemens and his Memorial teammates never considered this season a rebuilding one for the Mustangs despite returning very little from a year ago.

It may have looked that way early as the inexperience Mustangs took their lumps, going 6-8 in non-district games.

"When we were losing, I kept telling myself, 'We're going to get there,' " Clemens said.

Now in District 19-5A play, the Mustangs have found their groove. They end the first half in sole possession of first place after beating Katy 12-2 in five innings at home Thursday.

The two went in tied for first after Memorial lost to Seven Lakes and Katy beat Cinco Ranch. The Tigers didn't help themselves with four errors, but Memorial did plenty of damage before and after Katy's miscues.

"They had their 'A' game; we had our 'F' game," Katy coach Tom McPherson said. "So it wasn't much of a match. Hopefully, next time we play better against them."

Memorial (12-9, 6-1) graduated 16 seniors last season, with roughly half now playing Division I baseball. Some of its early-season losses came in blowout fashion.

The current seniors helped bridge the gap, stepping up when needed.

That was the case Thursday. Clemens went the distance on the mound, throwing 60 pitches in five innings. A botched rundown let the Tigers tie the game in the second inning, but Katy (18-4, 5-2) didn't threaten again until the fifth.

Even after two Memorial errors put Tigers on the corners with two out, Clemens (3-0) got a grounder to end it.

"My velocity is still not there, but my off-speed is doing really well," he said. "If you just hit your spots in high school, you're going to get batters out."

Clemens also homered in the third while most of Memorial's few returnees did their part. Matt Collins, Walker Pennington and Patrick Christie each reached and scored twice, while Tyler McCloskey went 2-for-3 with a three-run homer during a big second inning.

Memorial sent 10 batters to the plate, scoring six runs off three hits and two Katy errors. Five of the runs came with two outs.

"It was one of those deals where in this district, when you make errors, it's going to cost you," Memorial coach Jeremy York said. "We've been on the other end of that, so we know."